Eye-contact detector found in the brain

Why does making direct eye contact with someone give you that feeling of a special connection? Perhaps because it excites newly discovered "eye cells" in the amygdala, the part of the brain that processes emotions and social interactions.

This new type of neuron was discovered in a Rhesus macaque. If humans have these neurons too, it may be that they are impaired in disorders such as autism and schizophrenia, which affect eye contact and social interactions.

Katalin Gothard, a neurophysiologist at the University of Arizona in Tucson, and her team placed seven electrodes in the amygdala of a Rhesus macaque. The electrodes, each one-tenth the thickness of a human hair, allowed them to record activity in individual neurons as the macaque watched a video featuring another macaque. All the while, the team also tracked the macaque's gaze.

Out of the 151 neurons the researchers could distinguish, 23 fired only when the macaque was looking at the eyes of the monkey in the video. Of these neurons, which the team call "eye cells", four fired more when the monkey in the video appeared to be gazing back at the laboratory macaque, as if the two animals were making eye contact.

Tuned by evolution

"These are cells that have been tuned by evolution to look at the eye, and they extract information about who you are, and most importantly, are you making eye contact with me," says Gothard. Other eye cells fired depending on whether the monkey in the video was behaving in a friendly, aggressive or neutral manner, but not in response to eye contact.

Martha Farah, a cognitive neuroscientist at the University of Pennsylvania in Philadelphia, who was not involved in the work, says it is a "plausible hypothesis" that humans also have eye cells. "There are a lot of similarities between human and monkey visual systems," she says. "The human brain belongs to a species that is very social and very visual."

Gothard's group is going to investigate whether drugs can enhance the eye cells' activity in monkeys, suggesting possible therapies to treat conditions that involve reduced eye contact and social interactions. "But first we have to know more about them," she says. "We have just discovered their existence."

The team plans to try out the hormone oxytocin, which seems to boost social bonding. Oxytocin nasal spray is already being used as an experimental treatment for autism.

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Do our brains also have a dedicated circuit that activates on eye contact? (Image: Eye Candy/Rex Features)